Here, shops hate to be near competitors, and it's not unknown for them to lobby the local council over zoning infringements that their competitors are making. This is despite their competitors pulling in a lot of business. After all, shops will pay many times the rent to be in a mall, proximately because that's where the customers are, but ultimately because that's where the competition is.

OK, a small hamburger joint needs to worry if McDonalds sets up next door. But if another small hamburger joint sets up nearby, it will increase traffic. The "competition" isn't the guy next door. It's the guy next door, the food strip in the mall, and home-cooked food; and only the guy next door is pulling in foot-traffic to your area. But guess who most business owners will try to put out of business?

So now I'm wondering why this is only obvious once mentioned, and to what degree this sort of market/real-world ignorance features in various decisions about stating a business. You often don't know what you don't know, so how does one avoid these sorts of blinders?

One answer: try stuff where you can fail fast and (hopefully) cheap.

Try "is 100% responsible for"; if (in CA, USA) I decided to defy or ignore the zoning bureaucracy and open a gas station (or any "bricks and mortar" business within city limits), I think the 'crats would apply "corrective measures" (up to and including jail time) within days (if not hours or minutes). Although in practice, they'd notice long before that I was missing the multitudinous appropriate permits, and bring my efforts to a crashing halt.

As to why this most obvious explanation was missed: maybe the authors have thus far in their lives avoided contact with such bureaucracies?

I don't often see consecutive stations on the same side of the highway/road --tho I do occasionally (19th ave in SF, for example).